4. Quantum counting 3 marks Suppose f:{0,1}2n{0,1} with a promise that the number of solutions to f(x)=1 is either 2n or 2n+1. Explain how to decide, with high probability, whether there are 2n or 2n+1 solutions using a number of queries to Uf:x(1)f(x)x in O(2n)..